1. Field of the Invention
This invention relates to flexible couplings between an output shaft of a motor and an input shaft of a driven device. More specifically, this invention relates to flexible couplings with a one-way over-running clutch between the motor drive shaft and the driven device.
2. Discussion
Flexible couplings are used for transferring torque from output or drive shafts of an electrical motor or internal combustion engine to input shafts of various machines or devices, such as fans, packaging machines or pumps. Both the driving shaft and driven shaft are attached to jaw-type coupling members that have interlocking extensions to couple the motor to the machine. A typical flexible coupling has an elastomeric coupling "spider" placed between these input and output coupling members. The spider is a flexible element with several legs, each of which fits between the pairs of adjacent "teeth" of the coupling members, which provides the unit with a degree of flexibility during operation, while still transferring the torque from the driving shaft to the driven shaft. The coupling teeth allow for any axial offset while the flexibility of the spider reduces additional loads due to any angular mis-alignment between the motor and driven device. Without such a coupling, severe loading of the bearings in the motor or engine or in supportive "pillow blocks" could occur, causing reliability and durability problems.
During vibratory conditions that occur with certain driving means, such as internal combustion engines, the engine may have sudden large torque fluctuations. It is therefore desired to allow the driving shaft rotation to decelerate or even stop, relative to the driven shaft, while the driven shaft continues to rotate under the built up inertia of the driven device. In order to accomplish this, a clutch assembly is required between the output shaft of the motor and the input shaft of the driven device. This allows the driving shaft to stop, or even reverse direction, without suddenly stopping the rotation of the driven shaft. The driven device can then slow down under its own inertia, which avoids submitting the motor or engine to the sudden forces encountered in overcoming the substantial amount of inertia built up in the driven device.
Several one-way clutches or drives have been developed for use in other applications. For example, a one-way wrap spring clutch is disclosed in U.S. Pat. No. 5,598,913, issued to Monahan et al. The one-way over-running clutch pulley disclosed therein is applied to the rotational input shaft of the alternator, or other pulley driven device, and accommodates the inertia built up within an accessory and thereby cures the slipping and squealing of the belt when there is a large sudden deceleration of the engine.
Typically, a flexible coupling system includes a separate one-way drive or clutch which must be installed apart from the jaw-type coupling. An intermediate shaft is required, and in some cases, extra couplings to allow for additional misalignment and pillow blocks for support of one or more of the shafts may also be required. To reverse the direction of the one-way drive, the entire assembly must be dismantled. Therefore, the previous systems are complicated, expensive, and may also require a large physical space in which to include all of the necessary components.
In view of the foregoing attributes of the prior art devices, there exists a need in the art for an improved clutch assembly for use in a flexible coupling between an output shaft of a motor and a driven shaft of a machine.
It is therefore a primary object of this invention to fulfill that need by providing a flexible coupling with a clutch assembly that can be easily incorporated between the coupling members of the flexible coupling, reducing installation costs and complexity.
It is a further object of this invention to provide a flexible coupling that has a clutch assembly integrated therein such that it has generally the same overall dimensions as a conventional flexible coupling.
It is another object of this invention to provide a flexible coupling with an integrated clutch assembly so that the assembly does not require an intermediate shaft or additional shaft supports.
It is yet another object of this invention to provide a flexible coupling with a clutch assembly that is easily assembled and serviced.